Nirmalya Sengupta, the central character of Amit Chaudhuri's new novel, The Immortals, has elements of the writer's teenage self. This self carried a guitar and wrote poetry: growing up in a middle-class Bengali household in Bombay (Chaudhuri never says "Mumbai") was no insulation against adolescence. "I used to dress, as we call it in India, 'ethnically'. I wore an Indian-style coat, khadi stuff, and I just used to glare at people," Chaudhuri remembers. For a period in his youth, he tells me, he also had a quantity of facial hair. "Then I shaved one side of the moustache a little too much, so then had to shave the other side, and that's how I lost the moustache." Nirmalya undergoes a similar shearing at the end of The Immortals. He has left his hometown, Bombay, to go to university in London; after his arrival, he gives up his hair to an Italian barber off the Tottenham Court Road. It is a symbolic moment that has little effect - although he now looks completely (to use his own word) "normal", he is still not cured of his metaphysical turn of mind. Chaudhuri hasn't been either.

The Immortals is Chaudhuri's first novel for nine years, an interval he largely devoted to another of his passions, music. This is the kind of gap that editors find distressing, and indeed, as Chaudhuri points out with a tiny hint of pride, he has been described in this paper as a "publisher's nightmare". "I reacted against this professionalising of the author, in India and in Britain," he says. At one time he wanted to be a singer, and trained in the north Indian classical tradition. He has performed in India, Britain and America, and recently released an album, This Is Not Fusion, that explores the junctions between Indian classical and western popular traditions to frequently startling effect. As well as writing and performing music, he spent some time since A New World editing The Picador Book of Modern Indian Literature (2001), a huge project featuring 38 authors, including 20 translated from Indian languages into English. A short-story collection, Real Time, was published in 2002. Meanwhile, his first three novels - published in a single edition in the US under the title Freedom Song - won the Los Angeles Times book prize in 2003.

The Immortals is a more compendious novel than its predecessors - more peopled, more plotted - though it retains Chaudhuri's tender precision for the detail of bourgeois Bengali lives. It is preoccupied with music, and the question of how art should fit into the world. The adolescent Nirmalya - scruffy, serious, on the edge of pretentiousness - lives with his businessman father and housewife mother in a company flat in Bombay's upmarket Cuffe Parade. The family drive about the city in a company Mercedes: on Sundays they eat chilli-cheese toast at the Taj hotel. Music functions as an uncontrollable, estranging force in their otherwise calmly privileged lives. Nirmalya's mother, Mallika, has a beautiful voice, a talent that has been confined by her marriage. Nirmalya is a singer too and filled with the anxieties Chaudhuri once had. "My problem," as Chaudhuri recalls in his autobiographical poem "E-Minor", "was how to suffer, for I knew / Suffering to be essential to art; and yet / There was little cause for suffering. I had loving parents / and everything I required."

Chaudhuri's parents did not always have everything they required, having lost their assets during partition. They moved from Sylhet to Calcutta after the province became part of East Pakistan in 1947; Amit, their only child, was born in the city. The family later moved to Bombay with Chaudhuri's father's job: a chartered accountant, trained in Britain, he went on to become the assistant company secretary of the Britannia Biscuits Company, providing Chaudhuri with a childhood home full of bourbons and cream crackers (he once confessed in a poem to liking only Jammy Dodgers, though went on to marry a woman described by his mother as a "biscuit junkie"). In Bombay, the family lived in a company flat on Malabar Hill, which gave them access to the most desirable view in Bombay: the "Queen's Necklace", the lights of Marine Drive, where the edge of the city curves round the Arabian sea. "Popular culture, corporate culture, English rock sounds, pop songs, comic books, pornography, the nuclear family, my father's work, capitalism," says Chaudhuri, listing the materials of his life at that time.

In 1983, at the age of 20, he left Bombay and moved to Britain to take an English degree at University College London. He had been to England before, as a child, to visit an uncle and to have a heart murmur listened to by a series of English doctors. Returning by himself was a very different experience. At first he stayed at International Student House, and was a poetic oddity among students studying accountancy and management. Spending much of his time practising his singing, he felt inhibited, and paranoid about being overheard. "People are much more aware of one another in England, super-aware. They are focused on others in a seemingly detached and abstract way. This was very different from India. In India you could do anything and people would see you but not see you, hear you but not hear you."

So he moved into a bedsit in Warren Street, where he lived off unpleasant snacks eaten at peculiar times, and had anguished thoughts. "I would rarely go to class - I couldn't bring myself to interact with the other students. I didn't know where I stood." Instead he baited the Salvation Army with the temptation of a potential convert: fascinated by religion, he'd invite doorsteppers in when they knocked. "I'd want to talk to them about the mythic other, the metaphorical side of things. They were more interested in converting me." Throughout what might be called his Ginster years (Nirmalya, heating up pasties in his bedsit, finds "the first bite always burnt his lips"), he wrote a great deal of poetry. "I'd send my poems to national poetry competitions as advertised in the Poetry Review. Then I discovered that no one was getting in touch with me to congratulate me on having won the first prize. So I would switch on the radio. Just in case. I knew it was hilarious, even at the time." And yet, despite his loneliness and shyness, he retained his self-belief. "I knew I would survive," he says.

His optimism was vindicated at the end of his degree. His tutor, Dan Jacobson, showed his essays to Karl Miller, who was then the head of the English department. "I got a call from his secretary, to go and see him. I thought maybe I had done something wrong." In fact, Miller was impressed and encouraging. A week later, the results were due. Chaudhuri had got a first. "Three years of complete pointlessness ended in a hopeful way." He went back to India with an idea for a novel, about a boy going on his holidays from Bombay to Calcutta. For much of the next year, he lived in Bombay, writing. He sent an extract from the resulting manuscript to Miller, who published it in the London Review of Books, which he edited. The extract became the novella and short stories that form A Strange and Sublime Address (1991), Chaudhuri's first book, which won a Betty Trask award, the Commonwealth writer's prize, and admiration from a readership conditioned to expect the magical realism of Rushdie.

The success of Midnight's Children had skewed a generation of Indian writing in English towards grandeur, whimsicality and pickle factories: Chaudhuri's slender, focused novels could not be more different. "Rushdie represents a kind of hallucinatory cliff behind which we cannot see," Chaudhuri observed in an essay lamenting the effect of Rushdie's big book on its smaller, quieter antecedents. For him, Midnight's Children embodied "all that was most unserious about India - its loudness, its apparent lack of introspection and irony, its peculiar version of English grammar". Chaudhuri's work is in a different Indian tradition (critics have most commonly compared him to RK Narayan.) As Ian Jack, the former editor of Granta magazine, says: "You feel that he's not trying to describe 'India', but certain people in a certain place at a certain time. His books are about particularising things and people. They're calm. Details of behaviour and scene are memorably well done. Domestic life is shown to be subtle and complicated."

In 1987 Chaudhuri returned to Britain to take his doctorate at Balliol College, Oxford. His subject was DH Lawrence (whose influence is detectable throughout Chaudhuri's work). It was during this period that Chaudhuri met his wife, Rosinka Khastgir, who is now a fellow in cultural studies at the Centre for Studies in Social Sciences in Calcutta. They married in 1991. Chaudhuri's second novel, Afternoon Raag, was published two years later. It is clearly drawn from personal experience, being about an Indian student at Oxford and his memories of Calcutta.

For Chaudhuri the enchantment of Calcutta lay in "this kind of ironical relationship between middle-class banality - the middle-class commonplace - and the transcendental and the profound". He was drawn in by childhood memories of a place "at once vernacular and cosmopolitan - people speaking in Bengali but actually being much more modern and cosmopolitan than their counterparts speaking English in Bombay." He found his parents' generation exotic in their unanchoredness: "A class of people who are at once there and who are exiled, who are not completely there, who are travelling at the same time." This sense of ordinariness mingled with alienation permeates Afternoon Raag; the novel foregrounds place, weather and atmosphere in a profoundly unconventional way. Like a suburban Sunday afternoon, the story seems to stretch time in peculiar, pleasurable ways.

Chaudhuri's daughter, Aruna, was born in 1988; and that year he published his third novel, Freedom Song. Set in the winter of 1992, with tensions rising between the Hindu and Muslim communities in Calcutta , the novel follows the stories of two Hindu families. It opens with Khuku, a middle-aged woman, being woken by the call to prayer from a nearby mosque. Her friend Mimi has frank views on this: "They are going too far! And it isn't really Indian, it sounds like Bedouins." The novel picks at the anxieties and rationalisations that will lead Mimi to vote for the Hindu nationalist BJP, and substitutes gentle irony for outright condemnation.

The Chaudhuri family moved back to India in the late 1990s, choosing Calcutta for their home (although as a visiting professor in contemporary literature at the University of East Anglia, Chaudhuri is often away). He had never really lived there before, and it was no longer, it transpired, the place explored in many of his books - he found a faster-moving, less decayed city, altogether less dreamy. "It does like writers, but it's also Calcutta now, not the Calcutta of 25 or 30 or 100 years ago. They maybe haven't got over the idea of it, but the reality, the context that produced that, has disappeared." And he discovered, on his return, that he didn't quite fit in. "Something I realised once I went to Calcutta was that it wasn't home, and how much of an outsider I was. On the one hand, I was appropriated as a Bengali boy who was writing about Calcutta, on the other, I was regarded with a degree of suspicion." It is not the going overseas that is seen as strange, he tells me, but the decision to return. "To go to England or America and then to come back, that's not typical. Coming back is seen as a sign of failure, of not having done as well as you could have."

Something of this feeling of estrangement finds expression in the novella A New World (2000), which visits the city again through an outsider's eyes. The protagonist, Jayojit Chatterjee, is a lecturer in economics at an American university. After his marriage fails, he leaves the States to bring his young son on a visit to his parents in their shuttered Calcutta flat. As in all Chaudhuri's novels, a compulsive narrative is somehow generated from near-total eventlessness: unpacking suitcases, the afternoon nap, supper with Jayojit's retired parents. The Indian reviews were not particularly kind: the Hindustan Times felt the novel unfolded in "gruelling slow motion"; India Today criticised it as "somnambulist". It is not the kind of book that Jayojit himself would like: visiting a bookshop, he stares sceptically at some of the Indian novels: "'They not only look light, they feel lightweight as well,' he thought, weighing one in his hand." Among Jayojit's kind - the newly pragmatic and acquisitive middle class - there is a preference for size over substance; or so Chaudhuri seems to suggest.

He also feels that the Indian press haven't found a workable language to talk about value. "They criticise a lot, but the criticism is based on arguments about authenticity these days. 'Did he earn his right to talk about this? Is it really this street he's talking about? Should he have been talking about this particular street or a street which is more representative of this or that?'" He feels that imagination has become subservient to the social sciences, in insidious ways. "Margins and the centre, colonialism - it all has to fit into that."

Does he fit into that? "I fit in a bit uncomfortably," he says. "That's not to say there aren't people who like my work, but it's doing something different from, you know, the others. I see myself as fitting into a tradition, of giving a great deal of importance to space, of looking at time." The new elite are too far removed from metaphysics to make proper sense to him - they're obsessed with getting things done, with making things happen; thoughtfulness has been sidelined. "It's a very strange middle class," he says, speaking about contemporary India. "Full of operators and people on the move. It really doesn't value disruptions in that activeness. It doesn't have time for any privileging of daydreaming." Chaudhuri maintains an old-fashioned Bengali belief in the value and pleasure of getting there slowly, of circling the point. "I believe that the arts, and art, and writing, are basically forms of addiction - you go to them again, and you read it again, re-reading. And you're not re-reading for what the story tells you, for the plot, or illumination. This is not the addiction of what happens next."

Chaudhuri on Chaudhuri

"Later, he would enter the toilet, armed with an ashtray, a newspaper and a pair of reading-glasses. The toilet was his study. Here, filling the room with cigarette smoke, he read the significant news of the day; he pondered on 'world affairs' and 'home affairs'; he pontificated to himself on the 'current situation' from a Marxist angle. He was a water-closet thinker.

"This part of the daily ceremonies over, he would enter the bathroom to have his pre-luncheon bath, humming a small tune to himself. He would turn on the old, ineffectual shower and, suddenly elated, begin singing aloud to himself."

These sentences are about the central character, Chhotomama ("Junior Uncle"), in my first novel. I wrote them when I was still a graduate student at Oxford, and felt I'd arrived at a language I hadn't possessed before, with which to describe baths, balconies, human activities, and a bliss that was at once comic and serious. I sent the chapter to the LRB, where it appeared as a story. Of the sentence, "He was not so much an armchair philosopher as a water-closet thinker", Karl Miller said: "I don't think you need the 'armchair philosopher' bit." This terse observation was a guide when I began the nightmarish task of revision.